Gearbox for vehicle seat adjustment mechanism

ABSTRACT

A gearbox for a vehicle seat adjustment mechanism in accordance with the principles of the present disclosure includes first and second portions. The first portion includes a first body defining a first longitudinal recess and a first peripheral recess in fluid communication with the first longitudinal recess. The first body includes a concave first curved surface. The second portion includes a second body defining a second longitudinal recess and a second peripheral recess in fluid communication with the second longitudinal recess. The second body includes a convex second curved surface. The second curved surface has an equal and opposite curvature compared to the first curved surface. In an assembled configuration, the first and second curved surfaces are in contact, the first longitudinal and second longitudinal recesses cooperate to define a longitudinal passage, and the first and second peripheral recesses communicate to define a peripheral receptacle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/019,054, filed on May 1, 2020. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates to generally to gear drives case assemblies for vehicle seat adjusters and more particularly to a bi-directionally self-centered case for an orthogonal gear drive (e.g., of enveloping or helical type) used in adjusting longitudinal position of a vehicle seat.

BACKGROUND

This section provides background information related to the present disclosure and is not necessarily prior art.

Vehicles such as automobiles are commonly equipped with seat adjuster mechanisms, that can primarily adjust the height, tilt and/or longitudinal position of the driver or/and passenger seat, to accommodate occupants of different size and height as well as to provide a comfortable seating position to suit the occupant's preference. Such seat adjusters may be manually or powered operated.

Power operated seat adjusters are driven by electric motors, their size being directly linked to the torque they must provide to produce the required motion. Thus, if a reasonably high reduction gear ratio can be achieved in very limited space, smaller and faster electric motors can be used to providing the same level of mechanical power needed for the required function. Electric motors with increased speed and capable of delivering a certain level of torque, used in certain applications require a limited reduction gear ratio but in a very compact dimensional space.

Electric motor-driven adjusting devices offer various advantages over manual adjustment devices. User comfort may be enhanced. Electric motor-driven adjusting devices also provide an electric interface which lends itself to automation, e.g. under the control of a controller of a vehicle which may automatically control the motor to bring the seat to a desired state. In spite of the benefits offered by electric motor-driven adjusting devices, packaging is an issue in many seats.

Typically, a power operated seat length adjuster is actuated by an occupant-controlled switch and includes a bi-directional electric motor, mounted centrally or intermediately between the vehicle seat pair of track assemblies, that rotates two flex drive shafts extending outwardly from the motor to two gearbox blocks fixedly mounted inside of each upper or inner track assemblies. Each gearbox block includes a worm-worm gear or a worm-helical gear drive assembly, having the drive member actuated through the flex drive shaft and the driven member integral with an internal threaded spindle nut.

Each spindle drive assembly includes the already mentioned rotatable spindle nut that threadingly receives a lead screw extending longitudinally along and fixed to the lower or outer track assembly. Through these two drives, the electric motor rotational movement is orthogonally offset to move fore/and aft linearly the upper tracks relative to the lower tracks, along spindle screws axes. The vehicle seat is attached to on a frame supported by the seat pair of mobile upper tracks disposed parallel to one another, while the pair of lower tracks is fastened to the vehicle chassis. Typically, two drive shafts, gear boxes, lead screws, and drive nuts are employed in a power length adjuster drive, one set for each seat track assembly, driven by only one bi-directional electric motor.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

A gearbox for a vehicle seat adjustment mechanism in accordance with the principles of the present disclosure is provided. The gearbox includes a first portion and a second portion. The first portion includes a first body. The first body defines a first longitudinal recess and a first peripheral recess in fluid communication with the first longitudinal recess. The first body includes a first curved surface. The first curved surface is concave. The second portion includes a second body. The second body defines a second longitudinal recess and a second peripheral recess in fluid communication with the second longitudinal recess. The second body includes a second curved surface. The second curved surface is convex. The second curved surface has an equal and opposite curvature compared to the first curved surface. In an assembled configuration, the first curved surface is in contact with the second curved surface. In the assembled configuration, the first longitudinal recess communicates with the second longitudinal recess to define a longitudinal passage. In the assembled configuration, the first peripheral recess communicates with the second peripheral recess to define a peripheral receptacle.

In one implementation, the first curved surface and the second curved surface both define (i) a portion of an ellipsoidal surface, (ii) a portion of a conical surface, or (iii) a portion of a spherical surface.

In one implementation, the first curved surface and the second curved surface both define a portion of an ellipsoidal surface. The ellipsoidal surface has a first radius in a range of 190 mm to 200 mm and a second radius in a range of 240 to 250 mm.

In one implementation, the first curved surface and the second curved surface both define a portion of a conical surface. The conical surface defines an average opening angle in a range of 165° to 172°.

In one implementation, the first curved surface and the second curved surface both define a portion of a spherical surface. The spherical surface has a radius in a range of 190 mm to 200 mm.

In one implementation, one of the first portion and the second portion includes a frusto-conical projection extending from a respective one of the first curved surface and the second curved surface. The other of the first portion and the second portion includes a frusto-conical receptacle defined by a respective one of the first curved surface and the second curved surface. In the assembled configuration, the frusto-conical receptacle receives the frusto-conical projection.

In one implementation, the one of the first portion and the second portion further includes an annular projection extending from the respective one of the first curved surface and the second curved surface. The annular projection is disposed around a base of the frusto-conical projection. The annular projection is coaxial with the frusto-conical projection. The other of the first portion and the second portion further includes an annular depression defined by a respective one of the first curved surface and the second curved surface. The annular depression is coaxial with the frusto-conical receptacle. In the assembled configuration, the annular depression receives the annular projection.

In one implementation, the frusto-conical projection includes a first frusto-conical projection and a second frusto-conical projection. The frusto-conical receptacle includes a first frusto-conical receptacle and a second frusto-conical receptacle. The annular projection includes a first annular projection and a second annular projection. The annular depression includes a first annular depression and a second annular depression.

In one implementation, the gearbox further includes an elastic layer. The elastic layer is disposed on at least one of the first curved surface or the second curved surface.

In one implementation, one of the first portion and the second portion includes an integral rivet. The integral rivet extends from a respective one of the first curved surface and the second curved surface. The other one of the first portion and the second portion includes an aperture defined in a respective one of the first curved surface and the second curved surface, the aperture is configured to receive a portion of the integral rivet.

In one implementation, the gearbox further includes a plurality of fasteners. The plurality of fasteners is configured to couple the first portion and the second portion to each other.

In one implementation, the gearbox is configured to house at least a portion of a cross-axis gear system and a spindle screw. The cross-axis gear system includes a first gear in operative communication with a second gear. The second gear is in operative communication with the spindle screw.

In one implementation, the gearbox is a universal gearbox. The gear system is configured to operate at any one of: (i) a comfort speed has a linear adjusting speed ranging from 17 mm/s to 22 mm/s, (ii) a high speed has a linear adjusting speed ranging from 50 mm/s to 55 mm/s, or (iii) a ultra-high speed has a linear adjusting speed ranging from 80 mm/s to 85 mm/s.

In one implementation, the first gear is a cylindrical worm gear and the second gear is one of a helical gear or a single enveloping worm gear.

A vehicle seat adjustment assembly in accordance with the principles of the present disclosure is provided. The vehicle seat adjustment assembly includes a gearbox, a gear system, and a spindle screw. The gearbox assembly includes a first portion and a second portion. The first portion includes a first body. The first body defines a first longitudinal recess and a first peripheral recess in fluid communication with the first longitudinal recess. The first body includes a first curved surface. The first curved surface is concave. The second portion includes a second body. The second body defines a second longitudinal recess and a second peripheral recess. The second body includes a second curved surface. The second longitudinal recess cooperates with the first longitudinal recess to define a longitudinal passage. The second peripheral recess cooperates with the first peripheral recess to define a peripheral receptacle. The second curved surface is convex, has an equal and opposite curvature compared to the first curved surface, and is in contact with the first curved surface. The gear system includes a first gear and a second gear. The first gear is disposed at least partially within the peripheral receptacle. The first gear includes a first external thread. The first gear is configured to rotate about a first axis. The second gear is disposed at least partially within the longitudinal passage. The second gear includes external teeth and an internal thread. The second gear defines a gear passage. The external teeth are in operative communication with the first external thread. The second gear is configured to rotate about a second axis perpendicular to the first axis. The spindle screw extends through the gear passage. The spindle screw includes a second external thread. The second external thread is in operative communication with the internal thread.

In one implementation, the first curved surface and the second curved surface both define (i) a portion of an ellipsoidal surface, (ii) a portion of a conical surface, or (iii) a portion of a spherical surface.

In one implementation, the second gear is one of (i) a helical gear or (ii) a single enveloping worm gear.

In one implementation, the second external thread is a trapezoidal thread, and the spindle screw has a 3 mm lead, a 1.5 mm pitch, and one of a (i) 8 mm nominal diameter and (ii) a 9 mm nominal diameter.

In one implementation, the gear system is configured to operate at one of: (i) a comfort speed has a linear adjusting speed ranging from 17 mm/s to 22 mm/s, (ii) a high speed has a linear adjusting speed ranging from 50 mm/s to 55 mm/s, or (iii) a ultra-high speed has a linear adjusting speed ranging from 80 mm/s to 85 mm/s.

In one implementation, one of the first portion and the second portion includes a frusto-conical projection and an annular projection extending from a respective one of the first curved surface and the second curved surface. The annular projection is disposed around a base of the frusto-conical projection and coaxial with the frusto-conical projection. The other of the first portion and the second portion includes a frusto-conical receptacle and an annular depression defined by a respective one of the first curved surface and the second curved surface. The annular depression coaxial with the frusto-conical receptacle. The frusto-conical receptacle is configured to receive the frusto-conical projection and the annular depression is configured to receive the annular projection.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a partial perspective view of a vehicle seat assembly having a pair of seat track assemblies, each including a power seat length adjustment assembly in accordance with the principles of the present disclosure;

FIG. 2 is a perspective view of the power seat length adjustment assembly of FIG. 1;

FIG. 3 is an exploded perspective view of an adjustment subassembly of the power seat length adjuster assembly of FIG. 2;

FIGS. 4A-4E relate to a close-type gearbox having ellipsoidal mating surfaces in accordance with the principles of the present disclosure; FIG. 4A is a perspective view of the gearbox and a representative ellipsoid; FIG. 4B a perspective view of the gearbox; FIG. 4C is a first side view of the gearbox; FIG. 4D is a second side view of the gearbox; and FIG. 4E is an exploded perspective view of the gearbox;

FIGS. 5A-5B relate to an open-type gearbox having ellipsoidal mating surfaces in accordance with the principles of the present disclosure; FIG. 5A is a perspective view of the gearbox; and FIG. 5B is an exploded perspective view of the gearbox;

FIGS. 6A-6D relate to an open-type gearbox having conical mating surfaces in accordance with the principles of the present disclosure; FIG. 6A is a perspective view of the gearbox and a representative cone; FIG. 6B is a first side view of the gearbox; FIG. 6C is a second side view of the gearbox; and FIG. 6D is an exploded perspective view of the gearbox;

FIGS. 7A-7E relate to an open-type gearbox having spherical mating surfaces in accordance with the principles of the present disclosure; FIG. 7A is a perspective view of the gearbox and a representative sphere; FIG. 7B is a perspective view of the gearbox; FIG. 7C is a first side view of the gearbox; FIG. 7D is a second side view of the gearbox; and FIG. 7E is an exploded perspective view of the gearbox;

FIG. 8A-8B relate to preassembly join stop features; FIG. 8A is a detail perspective view of a depression of a preassembly join stop feature of the gearbox of FIG. 5B; and FIG. 8B is a detail perspective view of a protrusion of the preassembly join stop feature of FIG. 5B;

FIG. 9 is an exploded perspective view of a gearbox including a single join stop feature in accordance with the principles of the present disclosure;

FIG. 10 is an exploded perspective view of a gearbox that is free of preassembly join stop features in accordance with the principles of the present disclosure;

FIGS. 11A-11B relate to a gearbox including an elastic layer in accordance with the principles of the present disclosure; FIG. 11A is an exploded perspective view of the gearbox; and FIG. 11B is a perspective view of the gearbox;

FIGS. 12A-12C relate to a gearbox assembly including the gearbox of FIGS. 5A-5B assembled with screws in accordance with the principles of the present disclosure; FIG. 12A is a perspective view of the gearbox assembly; and FIG. 12B is a partial sectional view taken at line 12B-12B of FIG. 12A; FIG. 12C is a sectional view taken at line 12C-12C of FIG. 12A;

FIGS. 13A-13D relate to a gearbox assembly including the gearbox of FIGS. 5A-5B assembled with discrete rivets in accordance with the principles of the present disclosure; FIG. 13A is an exploded perspective view of the gearbox assembly with the rivets in an undeformed state; FIG. 13B is a perspective view of the gearbox assembly with the rivets in the undeformed state; FIG. 13C is a sectional view of the gearbox assembly taken at line 13C-13C of FIG. 13B, the rivets in the undeformed state; and FIG. 13D is a sectional view of the gearbox assembly taken at line 13D-13D of FIG. 13B, the rivets in a deformed state;

FIGS. 14A-14D relate to a gearbox assembly including a gearbox having integral rivets in accordance with the principles of the present disclosure; FIG. 14A is an exploded perspective view of the gearbox with the rivets in an undeformed state; FIG. 14B is a perspective view of the gearbox with the rivets in the undeformed state; FIG. 14C is a sectional view taken at line 14C-14C of FIG. 14B, the rivets in an undeformed state; and FIG. 14D is a sectional view taken at line 14D-14D of FIG. 14B, the rivets in a deformed state;

FIGS. 15A-15D relate to an enhanced-strength, enveloping-gear, comfort-speed power length adjustment assembly in accordance with the principles of the present disclosure; FIG. 15A is a partial perspective view of the adjustment assembly; FIG. 15B is a partial perspective cutaway view of the adjustment assembly; FIG. 15C is a sectional view of the adjustment assembly taken at line 15C-15C of FIG. 15A; and FIG. 15D is a sectional view of the adjustment assembly taken at line 15D-15D of FIG. 15A;

FIGS. 16A-16E related to an enhanced-strength, helical-gear, comfort-speed power length adjustment assembly in accordance with the principles of the present disclosure; FIG. 16A is a partial exploded perspective view of the adjustment assembly; FIG. 16B is a partial perspective view of the adjustment assembly; FIG. 16C is a partial perspective cutaway view of the adjustment assembly; FIG. 16D is a sectional view of the adjustment assembly taken at line 16D-16D of FIG. 16B; and FIG. 16E is a sectional view of the adjustment assembly taken at line 16E-16E of FIG. 16B;

FIGS. 17A-17D relate to a normal-strength, enveloping-gear, high speed power length adjustment assembly in accordance with the principles of the present disclosure; FIG. 17A is a partial perspective view of the adjustment assembly; FIG. 17B is a partial perspective cutaway view of the adjustment assembly; FIG. 17C is a sectional view of the adjustment assembly taken at line 17C-17C of FIG. 17A; and FIG. 17D is a sectional view of the adjustment assembly taken at line 17D-17D of FIG. 17A;

FIGS. 18A-18D relate to a normal-strength, helical-gear, high speed power length adjustment assembly in accordance with the principles of the present disclosure; FIG. 18A is a partial perspective view of the adjustment assembly; FIG. 18B is a partial perspective cutaway view of the adjustment assembly; FIG. 18C is a sectional view taken at line 18C-18C of FIG. 18A; and FIG. 18D is a sectional view taken at line 18D-18D of FIG. 18A; and

FIGS. 19A-19D relate to a normal-strength, helical-gear, ultra-high speed power length adjustment in accordance with to the principles of the present disclosure; FIG. 19A is a partial perspective view of the adjustment assembly; FIG. 19B is a partial perspective cutaway view of the adjustment assembly; FIG. 19C is a sectional view taken at line 19C-19C of FIG. 19A; and FIG. 19D is a sectional view taken at line 19D-19D of FIG. 19A.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings.

Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

With reference to FIG. 1, a seat assembly 10 is provided. The seat assembly 10 may include a seatback 12, a seat bottom 14, and one or more seat track assemblies 16. In some implementations, the seat assembly 10 is adjustably mounted to a vehicle (not shown), such as an automobile. For example, a reclining mechanism (not shown) may pivotably move the seatback 12 relative to the seat bottom 14, and the seat track assemblies 16 may translatably move the seat bottom 14 to a certain position relative to a vehicle floor pan (not shown). Accordingly, a user may selectively change the orientation of the seatback 12 relative to the seat bottom 14 using the reclining mechanism (not shown), and the position of the seat assembly 10 relative to the vehicle floor pan using the pair of seat track assemblies 16.

Each seat track assembly 16 may include a lower track 20, an upper track 22, and an adjustment assembly 24. The adjustment assembly 24 may be fixedly attached to a portion of the upper track 22 by one or more mechanical fasteners 26 (e.g., bolts, screws, rivets, etc.). In certain implementations the upper track 22 defines one or more cutouts (not shown) to accommodate the adjustment assembly 24.

The lower track 20 may be fixedly attached to a portion of the vehicle using one or more mechanical fasteners 28 (e.g., bolts, screws, rivets, etc.), or any other suitable fastening technique, and may define an axis A1. The lower track 20 may define a U-shaped profile extending in a direction substantially parallel to the axis A1 such that walls of the lower track 20 cooperate to define a central lower channel 30.

The upper track 22 may be fixedly attached to a portion of the seat bottom 14 using one or more mechanical fasteners 32 (e.g., bolts, screws, rivets, etc.), or any other suitable fastening technique. The upper track 22 may define a U-shaped profile extending in a direction substantially parallel to the axis A1 such that walls of the upper track 22 cooperate to define a central upper channel 34.

In an assembled configuration, as shown, the lower track 20 may support the upper track 22 for translation along the axis A1, such that the upper track 22 translates relative to the vehicle. For example, the lower track 20 may slidably support the upper track 22 for translation along the axis A1. The upper track 22 may translate relative to the lower track 20 to permit selective movement of the seatback 12 and the seat bottom 14 relative to the vehicle. Movement of the upper track 22 relative to the lower track 20 may be facilitated by a carriage assembly 50, including two pairs of ball-cage assemblies 52, which may be: (i) secured to the upper track 22 and/or the adjustment assembly 24, and (ii) at least partially received within the central lower channel 30 of the lower track 20.

With reference to FIG. 2, the adjustment assembly 24 may include a driver assembly 54, a spindle screw or lead screw 56, and an adjustment subassembly 58. In an assembled configuration, a portion of the adjustment assembly 24 may be secured relative to the vehicle and another portion of the adjustment assembly 24 may be secured relative to the upper track 22 to facilitate movement of the seatback 12 and the seat bottom 14 relative to the vehicle. For example, the spindle screw 56 may be secured to the lower track 20 and/or to the vehicle floor, while the adjustment subassembly 58 may be secured to the upper track 22. Accordingly, movement of the adjustment subassembly 58 relative to the spindle screw 56 causes the fore and aft movement of the upper track 22 and the seat bottom 14 relative to the lower track 20 and ultimately to the vehicle floor.

The driver assembly 54 may include an electric bi-directional motor and two flex drive shafts that transfer the speed and torque from the electric motor to the adjustment subassembly 58 to cause the movement of the adjustment subassembly 58 along the spindle screw 56 length and, thus, the fore-and-aft movement of the seat assembly 10 (FIG. 1), relative to the vehicle floor.

The spindle screw 56 may include a front end 62 and a rear end 64. In some implementations, the spindle screw 56 may define a substantially cylindrical rod defining an axis A2 extending from the front end 62 to the rear end 64 and having an outer thread 66 extending along and about the axis A2 from the front end 62 to the rear end 64. In an assembled configuration, the spindle screw 56 may be disposed within one or both of the central lower channel 30 of the lower track 20 and the central upper channel 34 of the upper track 22 such that the axis A2 is substantially parallel to the axis A1 (FIG. 1). The front end 62 and rear end 64 may be secured relative to the lower track 20 and/or to the vehicle floor through the studs rigidly mounted on the lower track 20. For example, the front end 62 may be supported by a front spindle bracket 68 that is secured to the lower track 20 and/or to the vehicle floor, and the rear end 64 may be supported by a rear spindle bracket 70 that is also secured to the lower track 20 and/or to the vehicle floor.

With reference to at least FIG. 3, the adjustment subassembly 58 may include a support frame 74, a housing assembly 76, a pair of bearing bushings 78, a first gear or cylindrical worm 80 having a helical outer thread 82 in mesh with external teeth 84 of a second gear or enveloping worm 86, a spindle nut integrally formed with the second gear 86 and having an internal thread 90, and the spindle screw 56 with the outer thread 66 (FIG. 2) engaging the internal thread 90 of the spindle nut. The first and second gears 80, 86 may be collectively referred to as a gear system or a gear assembly.

The support frame 74 may define a U-shape. The support frame 74 may include a base 100, a pair of walls 102 extending substantially perpendicular to the base 100 on opposing ends of the base 100, and a pair of flanges 104 extending substantially perpendicular to the pair of walls 102, respectively, and substantially parallel to the base 100. The base 100, walls 102, and flanges 104 may be integrally formed. The base 100 and walls 102 may cooperate to define an interior region 106. The pair of walls 102 may define a respective pair of wall apertures 108. The pair of flanges 104, may define a respective pair of flange apertures 110.

The housing assembly 76 may include a gearbox 114, a first cover shell 116, and a second cover shell 118 (also referred to as the “pair of cover shells 116, 118”). The first and second cover shells 116, 118 may be geometrically mirrored. The first and second cover shells 116, 118 may define respective first and second shell apertures 120, 122. The first and second cover shells 116, 118 may define first and second shell interior regions 124, 126, respectively.

The first and second cover shells 116, 118 may be formed from a resilient material having noise and vibration dampening characteristics. In some implementations, the first and second cover shells 116, 118 may be formed from a polymer such as rubber, for example. The use of rubber cover shells 116, 118, in compression against the walls 102 of the support frame 74, may increase the damping capability of the adjustment subassembly 58 in the process of vibration transmission to the seat structure.

The gearbox 114 may be formed from aluminum-zinc alloy die-casting material. The gearbox 114 may include a first part or portion 130 and a second part or portion 132. Each of the first and second portions 130, 132 may define a longitudinal recess 134, a peripheral recess 136, and an aperture 138. Each of the first and second portions 130, 132 further includes a curved mating surface 140. In an assembled state, the curved mating surfaces 140 of the first and second portions 130, 132 are in contact with each other, the longitudinal recesses 134 cooperate to define a longitudinal passage, and the peripheral recesses 136 cooperate to define a peripheral receptacle. The gearbox 114 may be secured in the assembled configuration by a plurality of fasteners 142 (e.g., screws, bolts, rivets, etc.). Various implementations of gearboxes are described in greater detail below.

The cylindrical worm 80 may define an axis of rotation A3 extending from a first end 150 to a second end 152. The helical outer thread 82 may be disposed about the axis of rotation A3 between the first and second ends 150, 152. In various implementations, the cylindrical worm 80 may be manufactured by an injection molding process from a plastic material such as PEEK 450G. The cylindrical worn 80 may be rotatably supported by the housing assembly 76. For example, the first end 150 of the cylindrical worm 80 may be rotatably disposed within the aperture 138 of the first portion 130 of the gearbox 114 and the second end 152 of the cylindrical worm 80 may be rotatably disposed within the aperture 138 of the second portion 132 of the gearbox 114.

The enveloping worm 86 may define an axis of rotation A4 extending from a first end 154 to a second end 156. The internal thread 90 and the external teeth 84 may be disposed about the axis of rotation A4. The bearing bushings 78 may include respective through-holes 160 that receive outer bearing surfaces 162 of enveloping worm 86. In the assembled configuration, the enveloping worm 86 and the bearing bushings 78 may be disposed at least partially within the longitudinal passage (formed by longitudinal recesses 134) of the gearbox 114. The enveloping worm 86 may be disposed between the bearing bushings 78 and rotatable with respect to the bearing bushings 78. The bearing bushings 78 may be rotatably fixed with respect to the gearbox 114 by engagement of radially-extending tabs 164 of the bearing bushings 78 with the gearbox 114.

In the assembled configuration, the gearbox 114 is disposed between the cover shells 116, 118 and at least partially within the shell interior regions 124, 126. The housing assembly 76, which includes the gearbox 114 and cover shells 116, 118, is disposed at least partially within the interior region 106 of the support frame 74. The spindle screw 56 (FIG. 2) extends through a gear passage 166 of the enveloping worm 86, the through-holes 160 of the bearing bushings 78, the longitudinal passage (formed by the longitudinal recesses 134), the first and second shell apertures 120, 122, and the wall apertures 108. The internal thread 90 of the enveloping worm 86 is threaded to the outer thread 66 (FIG. 2) of the spindle screw 56 (FIG. 2), and the external teeth 84 of the enveloping worm 86 are meshed with the helical outer thread 82 of the cylindrical worm 80.

The axis of rotation A4 of the enveloping worm 86 may be substantially parallel to and aligned with the axis A2 of the spindle screw 56. The axis of rotation A3 of the cylindrical worm 80 may be substantially perpendicular to the axes A2 and A4. In the assembled configuration, the adjustment subassembly 58 may be disposed within the central lower channel 30 of the lower track 20 and/or the central upper channel 34 of the upper track 22. The axes A2, A4 may be substantially parallel to and aligned with the axis A1.

Gearboxes

A gearbox according to the principles of the present disclosure may have one or more features to facilitate alignment of the two portions of the gearbox, distribute stresses, increase ease of assembly, improve accuracy of assembly, accommodate manufacturing tolerances, reduce or eliminate vibration and/or noise during use, and/or provide modularity to accommodate variety of gear assembly configurations, as will be described in greater detail below. More specifically, a gearbox according to the principles of the present disclosure may include curved mating surfaces, one or more preassembly join stop features, and/or an elastic layer, each of which is described in greater detail below.

Additionally, any of the gearboxes may be open-type gearboxes or close-type gearboxes. Close-type gearbox include a wall, such as a top wall, that at least partially encloses a worm gear. Close-type gearboxes may be used to reduce or eliminate contamination of gear systems inside the gearbox and/or eliminate noise during use of the gear system. In some implementations, a close-type gearbox may be used to facilitate noise reduction in an ultra-high speed gear system, which operates at a higher mesh frequency compared to lower speed gear systems. An example of a close-type gearbox is shown in FIGS. 4A-4E. Open-type gearboxes may be used in applications with low or no expected contamination and/or low expected noise. In some implementations, an open-type gearbox may be used with a comfort-speed or a high speed gear system that is not expected to emit significant noise during use. Examples of open-type gearboxes are shown in FIGS. 5A-7E, 9-11B, and 15A-19D.

The first and second portions of the gearbox may be manufactured in a die-casting process. The gearbox may comprise casting metal, such as an aluminum zinc alloy. The gearboxes may be assembled with various types of discrete or integral fasteners.

Curved Mating Surfaces

A two-part gearbox in accordance with the principles of the present disclosure may include curved mating surfaces. The mating curved surfaces may be defined by a portion of a three-dimensional curve, such as an ellipsoid, a cone, or a sphere. The two-part gearbox includes a first portion with a first curved mating surface and a second portion with a second curved mating surface. One of the mating surfaces is convex, while the other mating surface is concave. The mating surfaces may define the substantially the same shape, with equal and opposite curvature.

The mating surfaces may be self-centering in at least two orthogonal directions. In certain implementations, the mating surfaces are self-centering in three orthogonal directions (e.g., spherical mating surfaces). Accordingly, the curved mating surfaces may facilitate efficient assembly and preassembly with improved accuracy. Moreover, gearboxes having the self-centering mating surfaces may be free of certain other alignment features. In addition to facilitating alignment, the curved mating surfaces also increase surface area contact between the two gearbox portions, thereby improving a distribution of shear stress in the gearbox assembly during normal and/or shock loading conditions.

Referring to FIGS. 4A-4E, a gearbox 400 in accordance with the principles of the present disclosure is provided. The gearbox 400 includes a first part or portion 402 and a second part or portion 404. A boundary or joint 406 between the first and second portions 402, 404 defines a portion of an ellipsoid 408. The ellipsoid 408 may define a first or vertical radius and a second or horizontal radius. In certain implementations, the first radius is in a range of 190 mm to 200 mm and the second radius is in a range of 240 to 250 mm.

The first portion 402 includes a first body 410. The first body 410 includes a first exterior surface 412 and a first mating surface or curved surface 414. The first mating surface 414 is concave such that it curves inward 415, away from the second portion 404. The second portion 404 includes a second body 416. The second body 416 includes a second exterior surface 418 and a second mating surface or curved surface 420. The second mating surface 420 is convex such that it curves outward 421, toward the first portion 402. Curvatures of the first and second mating surfaces 414, 420 are substantially equal and opposite. More specifically, the first mating surface 414 is defined by a portion of a radial-outside 422 of the ellipsoid 408 and the second mating surface 420 is defined by a portion of a radial-inside 424 of the ellipsoid 408.

During pre-assembly of the gearbox 400, the mating surfaces 414, 420 may be configured to have a self-centering effect on the first and second portions 402, 404 to facilitate alignment of the first and second portions 402, 404. Prior to alignment during preassembly, the mating surfaces 414, 420 may be in less than complete contact (i.e., gaps may be present between the first and second mating surfaces 414, 420). One or both of the portions 402, 404 may be moved along a first orthogonal direction 426 and/or a second orthogonal direction 428 with respect to the other of the portions 402, 404 until the portions 402, 404 slide into alignment. This may be referred to as bi-directional self-centering. When the portions 402, 404 are aligned, the first and second mating surfaces 414, 420 may be in substantially continuous contact at the boundary 406.

The first body 410 of the first portion 402 defines a first longitudinal recess 440 and a first peripheral recess 442. The first longitudinal recess 440 and the first peripheral recess 442 are in fluid communication. The first body 410 includes a first wall 444. The first wall 444 at least partially defines the first peripheral recess 442. The first wall 444 may be partially cylindrical.

The second body 416 of the second portion 404 defines a second longitudinal recess 446 and a second peripheral recess 448. The second longitudinal recess 446 and the second peripheral recess 448 are in fluid communication. The second body 416 includes a second wall 450. The second wall 450 at least partially defines the second peripheral recess 448. The second wall 450 may be partially cylindrical.

The first and second longitudinal recesses 440, 446 cooperate to define a longitudinal passage 452 (FIGS. 4B-4C). The longitudinal passage 452 may extend continuously between first and second sides of the gearbox 400. When the gearbox 400 is assembled in a vehicle seat adjustment assembly, the longitudinal passage 452 may be aligned with axes of a lower track, spindle screw, and second gear (e.g., lower track 20, spindle screw 56, and second gear 86 of FIGS. 1-3). The longitudinal passage 452 may be configured to receive a second gear, a portion of a spindle screw, and bearing (e.g., second gear 86, spindle screw 56, and bearing bushings 78 of FIGS. 1-3).

The first and second peripheral recesses 442, 448 cooperate to define a peripheral receptacle 454 (FIG. 4C). The peripheral receptacle 454 is partially enclosed by the first and second walls 444, 450. Accordingly, gearbox 400 may be described as a close-type gearbox. The peripheral receptacle 454 may be configured to receive a first gear (e.g., first gear 80 of FIGS. 1-3). The first and second bodies 410, 416 may define respective first and second apertures 460, 462. The first and second apertures 460, 462 may be configured to support first and second bearing surfaces of a first gear (e.g., first gear 80 of FIGS. 1-3).

The first body 410 of the first portion 402 may define a plurality of third apertures 464. The second body 416 of the second portion 404 may define a plurality of fourth apertures 466. When the gearbox 400 is assembled, the third apertures 464 are axially aligned with the fourth apertures 466, respectively. The apertures 444, 466 may be configured to receive a plurality of fasteners, as will be described in greater detail below (see discussion accompanying FIGS. 12A-14D) to retain the gearbox 400 in the assembled configuration.

The gearbox 400 may further include a pair of pins 470 and a pair of receptacles 472. In the implementation shown, the pins 470 project from the second mating surface 420 of the second portion 404 and the receptacles 472 are defined in the first body 410 of the first portion 402. However, in other implementations, a first portion may include the pins while a second portion includes the receptacles. In some implementations, first and second portions may each include one pin and one receptacle.

The receptacles 472 may be blind holes. The pins 470 may be frusto-conical such that they have a largest diameter adjacent to the second body 416. The receptacles 472 may be frusto-conical such that they have a largest diameter at the first mating surface 414. The receptacles 472 may be configured receive respective pins 470 during preassembly of the gearbox 400. The pins 470 may be disposed in the receptacles 472 when the gearbox 400 is in the assembled configuration.

In various implementations, the gearbox 400 may further include one or more preassembly join stop features. For example, the gearbox 400 may include annular projections 480 to be received in annular depressions 482. The annular projections 480 may be coaxial with the pins 470 and the annular depressions 482 may be coaxial with the receptacles 472. A gearbox according to the principles of the present disclosure may be free of preassembly join stop features, include a single stop feature, include two stop features (e.g., the pair of annular projections 480 and the pair of annular depressions 482), as shown, or include more than two stop features. Pre-assembly join stop features are described in greater detail below in the discussion accompanying FIGS. 8A-10.

With reference to FIGS. 5A-5B, another gearbox 400 a is illustrated. The structure and function of the gearbox 400 a may be substantially similar to that of the gearbox 400, apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “a”) are used to identify those features that have been modified.

The gearbox 400 a includes a first part or portion 402 a and a second part or portion 404 a. A boundary or joint 406 a between the first and second portions 402 a, 404 a defines a portion of an ellipsoid 408.

The first portion 402 a includes a first body 410 a. The first body 410 a includes a first exterior surface 412 a and a first mating surface or curved surface 414 a. The first mating surface 414 a is concave. The second portion 404 a includes a second body 416 a. The second body 416 a includes a second exterior surface 418 a and a second mating surface or curved surface 420 a. The second mating surface 420 a is convex.

The first body 410 a of the first portion 402 a defines a first longitudinal recess 440 and a first peripheral recess 442 a. The first longitudinal recess 440 and the first peripheral recess 442 a are in fluid communication. The second body 416 a of the second portion 404 a defines a second longitudinal recess 446 and a second peripheral recess 448 a. The second longitudinal recess 446 and the second peripheral recess 448 a are in fluid communication.

The first and second longitudinal recesses 440, 446 cooperate to define a longitudinal passage 452 (FIG. 5A). The first and second peripheral recesses 442 a, 448 a cooperate to define a peripheral receptacle 454 a (FIG. 5A). The peripheral receptacle 454 a is open to an exterior region 500 of the gearbox 400 a at a peripheral opening 502 defined by the first and second bodies 410 a, 416 a when the gearbox 400 a is in the assembled configuration. Accordingly, the gearbox 400 a may be described as an open-type gearbox. The peripheral receptacle 454 a may be configured to at least partially receive a first gear (e.g., first gear 80 of FIGS. 1-3), such as in first and second apertures 460, 462 that support first and second bearing surfaces of the first gear. A portion of the first gear may project from the gearbox 400 a through the peripheral opening 502.

The gearbox 400 a may further include third and fourth apertures 464, 466 for receiving fasteners, pins 470 and receptacles 472, and annular projections and depressions 480, 482 as shown and as described above in the discussion accompanying FIGS. 4A-4E.

Referring to FIGS. 6A-6D, another gearbox 400 b is illustrated. The structure and function of the gearbox 400 b may be substantially similar to that of the gearbox 400 a, apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “b”) are used to identify those features that have been modified.

The gearbox 400 b includes a first part or portion 402 b and a second part or portion 404 b. A boundary or joint 406 b between the first and second portions 402 b, 404 b defines a portion of a cone 600. In certain implementations, the cone 600 may define an opening angle ranging from 165° to 172°.

The first portion 402 b includes a first body 410 b. The first body 410 b includes a first exterior surface 412 a and a first mating surface or curved surface 414 b. The first mating surface 414 b is concave such that it curves inward 415, away from the second portion 404 b. The second portion 404 b includes a second body 416 b. The second body 416 b includes a second exterior surface 418 a and a second mating surface or curved surface 420 b. The second mating surface 420 b is convex such that it curves outward 421, toward the first portion 402 b. Curvatures of the first and second mating surfaces 414 b, 420 b are substantially equal and opposite.

During pre-assembly of the gearbox, the mating surfaces 414 b, 420 b may be configured to have a self-centering effect on the first and second portions 402 b, 404 b to facilitate alignment of the first and second portions 402 b, 404 b. Prior to alignment during preassembly, the mating surfaces 414 b, 420 b may be in less than complete contact (i.e., there may be gaps between the first and second mating surfaces 414 b, 420 b). One or both of the portions 402 b, 404 b may be moved along a first orthogonal direction 426 and/or a second orthogonal direction 430 with respect to the other of the portions 402 b, 404 b until the portions 402 b, 404 b slide into alignment. This may be referred to as bi-directional self-centering. When the portions 402 b, 404 b are aligned, the first and second mating surfaces 414 b, 420 b may be in substantially continuous contact at the boundary 406 b.

The first body 410 b of the first portion 402 b defines a first longitudinal recess 440 and a first peripheral recess 442 a. The first longitudinal recess 440 and the first peripheral recess 442 a are in fluid communication. The second body 416 b of the second portion 404 b defines a second longitudinal recess 446 and a second peripheral recess 448 a. The second longitudinal recess 446 and the second peripheral recess 448 a are in fluid communication. The first and second longitudinal recesses 440, 446 cooperate to define a longitudinal passage 452 (FIG. 6A-6B). The first and second peripheral recesses 442 a, 448 a cooperate to define a peripheral receptacle 454 a (FIG. 6A). While the gearbox 400 a is shown as an open-type gearbox, in other implementations, it may include walls similar or identical to the walls 444, 450 of the gearbox 400 (FIGS. 4A-4E) and be a close-type gearbox.

The gearbox 400 b may further include third and fourth apertures 464, 466 for receiving fasteners, pins 470 and receptacles 472, and annular projections and depressions 480, 482 as shown and as described above in the discussion accompanying FIGS. 4A-4E.

Referring to FIGS. 7A-7E, another gearbox 400 c is illustrated. The structure and function of the gearbox 400 c may be substantially similar to that of the gearbox 400 a, apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “c”) are used to identify those features that have been modified.

The gearbox 400 c includes a first part or portion 402 c and a second part or portion 404 c. A boundary or joint 406 c between the first and second portions 402 c, 404 c defines a portion of a sphere 700. In certain implementations, the sphere 700 may define a radius in a range of 190 mm to 200 mm.

The first portion 402 c includes a first body 410 c. The first body 410 c includes a first exterior surface 412 a and a first mating surface or curved surface 414 c. The first mating surface 414 c is concave such that it curves inward 415, away from the second portion 404 c. The second portion 404 c includes a second body 416 c. The second body 416 c includes a second exterior surface 418 a and a second mating surface or curved surface 42 bc. The second mating surface 420 c is convex such that it curves outward 421, toward the first portion 402 c. Curvatures of the first and second mating surfaces 414 c, 420 c are substantially equal and opposite.

During pre-assembly of the gearbox, the mating surfaces 414 c, 420 c may be configured to have a self-centering effect on the first and second portions 402 c, 404 c to facilitate alignment of the first and second portions 402 c, 404 c. Prior to alignment during preassembly, the mating surfaces 414 c, 420 c may be in less than complete contact (i.e., there may be gaps between the first and second mating surfaces 414 c, 420 c). One or both of the portions 402 c, 404 c may be moved along a first orthogonal direction 426, a second orthogonal direction 430, and/or a third orthogonal direction 702 with respect to the other of the portions 402 c, 404 c until the portions 402 c, 404 c slide into alignment. This may be referred to as three-directional self-centering. When the portions 402 c, 404 c are aligned, the first and second mating surfaces 414 c, 420 c may be in substantially continuous contact at the boundary 406 c.

The first body 410 c of the first portion 402 c defines a first longitudinal recess 440 and a first peripheral recess 442 a. The first longitudinal recess 440 and the first peripheral recess 442 a are in fluid communication. The second body 416 c of the second portion 404 c defines a second longitudinal recess 446 and a second peripheral recess 448 a. The second longitudinal recess 446 and the second peripheral recess 448 a are in fluid communication. The first and second longitudinal recesses 440, 446 cooperate to define a longitudinal passage 452 (FIG. 7B-7C). The first and second peripheral recesses 442 a, 448 a cooperate to define a peripheral receptacle 454 a (FIG. 7B). While the gearbox 400 c is shown as being an open-type gearbox, in other implementations, the gearbox 400 c may include walls similar or identical to the walls 444, 446 of the gearbox 400 (FIGS. 4A-4E) and be a close-type gearbox.

The gearbox 400 c may further include third and fourth apertures 464, 466 for receiving fasteners, pins 470 and receptacles 472, and annular projections and depressions 480, 482 as shown and as described above in the discussion accompanying FIGS. 4A-4E.

Preassembly Join Stop Features

Gearboxes according to the principles of the present disclosure may include one or more features to facilitate preassembly and offer flexibility to accommodate manufacturing tolerances. Gearboxes may include a single preassembly join stop feature, a double preassembly join stop feature, or more than two preassembly join stop features. In various implementations, a gearbox may be free of preassembly join stop features.

Referring to FIG. 8A, a portion of the second body 416 a of the gearbox 400 a of FIG. 5A is shown. The portion includes the pin 470 and the annular projection 480. In various implementations, the pin 470 and the annular projection 480 may be integrally formed with the second body 420 a.

The pin 470 projects from the second mating surface 420 a. The pin 470 may have a frusto-conical shape such that it has a larger diameter at a proximal end or base, closer to the second mating surface 420 a and a smaller diameter at a distal end 800 further from the second mating surface 420 a. The pin 470 includes a first joint surface 802 that is frusto-conical.

The annular projection 480 may have a larger radius than the pin 470 and extend circumferentially around the base of the pin 470. The annular projection may extend axially from the second mating surface 420 a toward the distal end 800 of the pin 470. However, the annular projection 480 may extend axially along only a portion of a length of the pin 470. The annular projection 480 includes a second joint surface 804.

With reference to FIG. 8B, the first body 410 a includes the receptacle 472 and the annular depression 482. The receptacle 472 may be defined by the first mating surface 414 a. The receptacle 472 may have a frusto-conical shape such that it has a larger diameter at a proximal end 806 at the first mating surface 414 a and a smaller diameter at a distal end 808 offset from the first mating surface 414 a. The receptacle 472 includes a third joint surface 810 that is frusto-conical.

The annular depression 482 may have a larger radius than the receptacle 472 and extend circumferentially around a portion of the receptacle. The annular depression may extend axially from the first mating surface 414 a toward the distal end 808 of the receptacle 472. However, the annular depression 482 may extend axially along only a portion of a length of the receptacle 472. The annular depression 482 may include a fourth joint surface 812.

When the gearbox 400 a (FIG. 5A) is in an assembled or preassembled configuration, the pin 470 is received in the receptacle 472. The first joint surface 802 of the pin 470 may engage the third joint surface 810 of the receptacle 472. The annular projection 480 is received in the annular depression 482. The second joint surface 814 of the annular projection 480 may engage the fourth joint surface 812 of the annular depression 482. Collectively, the annular projection 480 and the annular depression 482 may be referred to as a preassembly join stop feature.

Returning to FIG. 5A, the gearbox 400 a may include two preassembly join stop features, such as the two pairs of annular projections and depressions 480, 482. That is, the gearbox 400 a may have double join stop features. The first portion 402 a may include the receptacles 472 and the annular depressions 482 and the second portion 404 a may include the pins 470 and the annular projections 480, as shown. In various other implementations, a first portion may include pins and projections while a second portion includes receptacles and depressions. In various other implementations, both first and second portions may include pins, annular projections, receptacles, and annular depressions.

With reference to FIG. 9, another gearbox 400 d is illustrated. The structure and function of the gearbox 400 d may be substantially similar to that of the gearbox 400 a, apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “d”) are used to identify those features that have been modified.

The gearbox 400 d includes a first part or portion 402 d and a second part or portion 404 d. A boundary or joint (see, e.g., boundary 406 a of FIG. 5A) between the first and second portions 402 d, 404 d defines a three-dimensional curve, such as a portion of one of an ellipsoid, a cone, or a sphere.

The first portion 402 d includes a first body 410 d. The first body 410 d includes a first exterior surface 412 a and a first mating surface or curved surface 414 d. The second portion 404 d includes a second body 416 d. The second body 416 d includes a second exterior surface 418 a and a second mating surface or curved surface 420 d. One of the first and second mating surfaces 414 d, 420 d is concave and the other of the first and second mating surfaces 414 d, 420 d is convex.

The first body 410 d of the first portion 402 d defines a first longitudinal recess 440 and a first peripheral recess 442 a. The first longitudinal recess 440 and the first peripheral recess 442 a are in fluid communication. The second body 416 d of the second portion 404 d defines a second longitudinal recess 446 and a second peripheral recess 448 a. The second longitudinal recess 446 and the second peripheral recess 448 a are in fluid communication.

The first and second longitudinal recesses 440, 446 cooperate to define a longitudinal passage (see, e.g., longitudinal passage 452 of FIG. 5A). The first and second peripheral recesses 442 a, 448 a cooperate to define a peripheral receptacle (see e.g., peripheral receptacle 454 a of FIG. 5A). While the gearbox 400 d is shown as being an open-type gearbox, the gearbox 400 d may further include walls similar to the walls 444, 446 of the gearbox 400 of FIGS. 4A-4E and be a close-type gearbox. The gearbox 400 d may further include third and fourth apertures 464, 466 for receiving fasteners.

The second portion 404 d may include a pin 470 and a pin 470 d. An annular projection 480 may extend around a portion of the pin 470, as described above in the discussion accompanying FIGS. 8A-8B. The pin 470 d may extend from the second mating surface 420 d between a proximal end or base 900 and a distal end 902. The pin 470 d may include a first joint surface 904 extending between the proximal end 900 and the distal end 902.

The first portion 402 d may include a receptacle 472 and a receptacle 472 d. An annular depression 482 may extend around a portion of the receptacle 472, as described above in the discussion accompanying FIGS. 8A-8B. The receptacle 472 d may extend into the first mating surface 414 d from a proximal end 906 to a distal end (not shown). The receptacle 472 d may include a second joint surface 910 extending between the proximal end 906 and the distal end.

When the gearbox 400 d is in an assembled or preassembled configuration, the receptacle 472 d receives the pin 470 d. The first joint surface 904 may engage the second joint surface 910. The gearbox 400 d includes a single preassembly join stop feature (e.g., the annular projection and depression 480, 482). Accordingly, the gearbox 400 d may be asymmetric about a plane that extends through a center axis 912 and between a top 914 and bottom 916 of the gearbox 400 d. Although the annular projection and depression 480, 482 are shown on a first side 918 of the plane, in various other implementations, the annular projection and depression 480, 482 may alternatively be on a second side 920 of the plane.

With reference to FIG. 10, another gearbox 400 e is illustrated. The structure and function of the gearbox 400 e may be substantially similar to that of the gearbox 400 d, apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “e”) are used to identify those features that have been modified.

The gearbox 400 e includes a first part or portion 402 e and a second part or portion 404 e. A boundary or joint (see, e.g., boundary 406 a of FIG. 5A) between the first and second portions 402 e, 404 e defines a three-dimensional curve, such as portion of one of an ellipsoid, a cone, or a sphere.

The first portion 402 d includes a first body 410 e. The first body 410 e includes a first exterior surface 412 a and a first mating surface or curved surface 414 e. The second portion 404 e includes a second body 416 e. The second body 416 e includes a second exterior surface 418 a and a second mating surface or curved surface 420 e. One of the first and second mating surfaces 414 e, 420 e is concave and the other of the first and second mating surfaces 414 e, 420 e is convex.

The first body 410 e of the first portion 402 e defines a first longitudinal recess 440 and a first peripheral recess 442 a. The first longitudinal recess 440 and the first peripheral recess 442 a are in fluid communication. The second body 416 e of the second portion 404 e defines a second longitudinal recess 446 and a second peripheral recess 448 a. The second longitudinal recess 446 and the second peripheral recess 448 a are in fluid communication.

The first and second longitudinal recesses 440, 446 cooperate to define a longitudinal passage (see, e.g., longitudinal passage 452 of FIG. 5A). The first and second peripheral recesses 442 a, 448 a cooperate to define a peripheral receptacle (see e.g., peripheral receptacle 454 a of FIG. 5A). While the gearbox 400 e is shown as an open-type gearbox, the gearbox 400 e may, in other implementations, further include walls similar or identical to the walls 444, 446 of the gearbox 400 of FIGS. 4A-4E and be a close-type gearbox. The gearbox 400 e may also include third and fourth apertures 464, 466 for receiving fasteners.

The second portion 404 e may include two pins 470 d. The first portion 402 d may include two receptacles 472 d. When the gearbox 400 e is in an assembled or preassembled configuration, the receptacles 472 d receive the pins 470 d, respectively. The gearbox 400 e may be symmetric about a plane that extends through a center axis 912 and between a top 914 and bottom 916 of the gearbox 400 e. The gearbox 400 e may be free of preassembly join stop features (e.g., one or more pairs of annular projections and depressions 480, 482 as shown at least in FIGS. 8A-9).

Elastic Layer

A gearbox according to the principles of the present disclosure may further include an elastic layer on a first mating surface and/or a second mating surface. The elastic layer may, in various implementations, be referred to as a compensation elastic element. The elastic layer facilitates accommodation of relatively large manufacturing tolerances in the bodies of the gearbox portions, and more particularly in the mating surfaces. An elastic layer may be particularly beneficial when used in a gearbox without preassembly join stop features (see, e.g., gearbox 400 e of FIG. 10), but may also be used on gearboxes with preassembly join stop features (see, e.g., gearboxes 400 a, 400 d). The elastic element may comprise an elastic material, such as nitrile butadiene rubber, having a predefined compression hardness.

With reference to FIGS. 11A-11B, another gearbox 400 f is illustrated. The structure and function of the gearbox 400 f may be substantially similar to that of the gearbox 400 e, apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “f”) are used to identify those features that have been modified.

The gearbox 400 f includes a first part or portion 402 e and a second part or portion 404 f. A boundary or joint 406 f between the first and second portions 402 f, 404 f defines a three-dimensional curve, such as a portion of one of an ellipsoid, a cone, or a sphere. The first portion 402 e includes a first body 410 e and the second portion 404 f includes a second body 416 e. The first and second bodies 410 e, 416 e include first and second mating surfaces 414 e, 420 e, respectively,

The second portion 404 f further includes an elastic layer 1100. The elastic layer 1100 may be disposed on the second mating surface 420 e, such as directly on the second mating surface 420 e. The elastic layer 1100 may be coupled to the second mating surface 420 e. The elastic layer 1100 may have a substantially uniform thickness. For example, the elastic layer 1100 may define a thickness 1102 ranging from 1 mm to 1.5 mm.

In other implementations, an elastic layer may additionally or alternatively be present on a first mating surface of a second portion. The use of an elastic layer, such as the elastic layer 1100, may be equally applicable to open-type or close-type gearboxes, having any mating surface curvature (e.g., ellipsoidal, conical, spherical), and any number of preassembly join stop features, including none.

Fasteners

A gearbox assembly according to the principles of the present disclosure may include any of the gearboxes discussed above and a plurality of fasteners. The fasteners may include screws, rivets, and/or bolts, by way of example. Rivets may be discrete components separate from the gearbox portions. Additionally or alternatively, one or both of the first and second portions may include built-in or integral rivets. A gearbox may include more than one type of fastener, such as any combination of the fasteners described herein.

With reference to FIGS. 12A-12C, a gearbox assembly 1200 according to the principles of the present disclosure is provided. The gearbox assembly 1200 includes the gearbox 400 a (see FIGS. 5A-5B and accompanying discussion) and a plurality of fasteners 1202. The fasteners 1202 may include screws, such as self-tapping screws. In some implementations, the plurality of fasteners 1202 may include four fasteners.

As best shown in FIG. 12B, each fastener 1202 may include a shaft 1204, a head 1206, and a thread 1208 extending along at least a portion of the shaft 1204. The shaft 1204 may extend through third and fourth apertures 464, 466. The head 1206 may be disposed at least partially in a countersink 1210 in the second body 416 a such that an end 1212 of the head 1206 is flush with at least a portion of the exterior surface 412 a of the second body 416 a. The thread 1208 may engage a surface 1214 of the third aperture 464 to couple the first and second portions 402 a, 404 a to each other. In the assembled configuration, as shown in FIG. 12C, the pins 470 and annular projections 480 may be disposed in the receptacles 472 and annular depressions 482, respectively. In other implementations, an orientation of the screws 1202 may be reversed so that the head 1206 engages the first body 410 a and the thread 1208 engages the second body 416 a.

Although FIGS. 12A-12C depict the gearbox assembly 1200 including the open-type gearbox having ellipsoidal mating surfaces and double preassembly join stop features, the use of screws is equally applicable to assemble other gearboxes according to the principles of the present disclosure. For example, a gearbox assembly may include screws and a gearbox that (i) is open-type or close-type, (ii) has ellipsoidal, conical, spherical, or other three-dimensional curved mating surfaces, (iii) includes zero, one, two, or more than two preassembly join stop features, and (iv) includes an elastic layer or is free of an elastic layer.

Referring to FIGS. 13A-13D, a gearbox assembly 1300 according to the principles of the present disclosure is provided. The gearbox assembly 1300 includes the gearbox 400 e (see FIG. 10 and accompanying discussion) and a plurality of fasteners 1302. The fasteners 1302 may include rivets. Prior to assembly and deformation, each of the rivets may be a distinct and separable component. In some implementations, the plurality of fasteners 1302 may include four rivets.

As best shown in FIG. 13C, each fastener 1302 may include a shaft 1304 and a head 1306. The shaft 1304 may include a tail 1308 that is configured to be buckled, upset, or deformed to form a secondary head 1308′, thereby transitioning the fastener 1302 from an undeformed state to a deformed state. The shaft 1304 may extend through third and fourth apertures 464, 466. The head 1306 may be disposed at least partially in a countersink 1310 in the first body 410 e such that an end 1312 of the head 1306 is flush with at least a portion of the first exterior surface 412 a of the first body 410 e.

When the rivets 1302 are in the undeformed state, as shown in FIGS. 13A-13C, the tail 1308 projects past the second exterior surface 418 a. When the rivets 1302 are in a deformed state, as shown in FIG. 13D, the secondary head 1308′ may be disposed in a countersink 1314 on in the second body 416 e such that an end 1316 of the secondary head 1308′ is flush with the second exterior surface 418 a of the second body 416 e. In the deformed state, the rivets 1302 retain the gearbox 400 e in the assembled state by coupling the first and second portions 402 e and 404 e to one another. In other implementations, an orientation of the rivets 1302 may be reversed so that the head 1306 engages the second body 416 e and the secondary head 1308′ engages the first body 410 e.

Although FIGS. 13A-13D depict the gearbox assembly 1300 including the open-type gearbox having ellipsoidal mating surfaces and being free of preassembly join stop features, the use of rivets is equally applicable for assembly other gearboxes according to the principles of the present disclosure. For example, a gearbox assembly may include rivets and a gearbox that (i) is open-type or close-type, (ii) has ellipsoidal, conical, spherical, or other three-dimensional curved mating surfaces, (iii) includes zero, one, two, or more than two preassembly join stop features, and (iv) includes an elastic layer or is free of an elastic layer.

Referring to FIGS. 14A-14D, a gearbox assembly 1400 according to the principles of the present disclosure is provided. The gearbox assembly 1400 includes a gearbox 400 g having integral rivets. The structure and function of the gearbox 400 g may be substantially similar to that of the gearbox 400 a, apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “g”) are used to identify those features that have been modified.

The gearbox 400 g includes a first part or portion 402 g and a second part or portion 404 g. A boundary or joint 406 g between the first and second portions 402 g, 404 g defines a portion of a three-dimensional curve, such as an ellipsoid, a cone, or a sphere. The first portion 402 g includes a first body 410 g. The first body 410 g includes a first exterior surface 412 a and a first mating surface or curved surface 414 g. The second portion 404 g includes a second body 416 g. The second body 416 g includes a second exterior surface 418 a and a second mating surface or curved surface 420 g. One of the first and second mating surfaces 414 g, 420 g is concave and the other of the first and second mating surfaces 414 g, 420 g is convex. Curvatures of the first and second mating surfaces 414 g, 420 g are substantially equal and opposite.

The first body 410 g of the first portion 402 g defines a first longitudinal recess 440 and a first peripheral recess 442 a. The first longitudinal recess 440 and the first peripheral recess 442 a are in fluid communication. The second body 416 g of the second portion 404 g defines a second longitudinal recess 446 and a second peripheral recess 448 a. The second longitudinal recess 446 and the second peripheral recess 448 a are in fluid communication. The first and second longitudinal recesses 440, 446 cooperate to define a longitudinal passage 452 (FIG. 14B). The first and second peripheral recesses 442 a, 448 a cooperate to define a peripheral receptacle 454 a (FIG. 14B). While the gearbox 400 g is shown as being an open-type gearbox, the gearbox 400 g may, in other implementations, include walls similar or identical to the walls 444, 446 of the gearbox 400 of FIGS. 4A-4E and be a close-type gearbox.

The second portion 404 g may include a first pair of integral rivets 1402 and a second pair of integral rivets 1404. The first and second pairs of rivets 1402, 1404 may be integrally formed with the second body 416 g. The first and second pairs of rivets 1402, 1404 may extend from the second mating surface 420 g. The rivets 1402, 1404 may have circular or oval cross sections. In the implementation shown, the rivets 1402 of the first pair have circular cross sections and the rivets 1404 of the second pair have oval cross sections.

The first portion 402 g may include a first pair of rivet apertures 1406 and a second pair of rivet apertures 1408. The first and second pairs of rivet apertures may be defined in the first mating surface 414 g. The rivet apertures 1406, 1408 may have cross-sectional shapes that match respective cross-sectional shapes of the rivets 1402, 1404. In the embodiment shown, the rivet apertures 1406 of the first pair have a circular cross section and the rivet apertures 1408 of the second pair have an oval cross section.

The first and second pairs of rivet apertures 1406, 1408 may be configured to receive the first and second pairs of rivets 1402, 1404, respectively. Prior to deformation, while in a preassembled configuration, the rivets 1402, 1404 may project beyond the first exterior surface 412 a, as shown in FIGS. 14B-14C. In an assembled configuration, the rivets 1402, 1404 are buckled, upset, or deformed into a deformed state. More specifically, respective first and second tails 1410, 1412 (FIG. 14C) of the rivets 1402, 1404 of the first and second pairs may be deformed into respective first and second heads 1410′, 1412′ (FIG. 14D). The first and second heads 1410′, 1412′ may be disposed in respective first and second countersinks 1414, 1416 in the first exterior surface 414 a.

In other implementations, locations of the rivets and rivet apertures may be reversed so that the first portion includes rivets and the second portion includes rivet apertures. In some implementations, both first and second portions include rivets and rivet apertures.

Although FIGS. 14A-14D depict the gearbox assembly 1400 including the open-type gearbox including double preassembly join stop features, the inclusion of integral rivets is equally applicable for assembly other gearboxes according to the principles of the present disclosure. For example, a gearbox assembly may include integral rivets on a gearbox that (i) is open-type or close-type, (ii) has ellipsoidal, conical, spherical, or other three-dimensional curved mating surfaces, (iii) includes zero, one, two, or more than two preassembly join stop features, and (iv) includes an elastic layer or is free of an elastic layer.

Gear Assemblies

Gearboxes according to the principles of the present disclosure are configured to accommodate a variety of different gear assembly configurations. In various implementations, a single universal gearbox is configured to accommodate a gear system including any combination of the following features. For example, gearboxes according to the principles of the present disclosure may (i) include a cross-axis single enveloping gear system or a cross-axis helical gear system, (ii) be normal-strength or enhanced-strength, and (iii) be configured to operate within a comfort speed range, a high speed range, or a ultra-high speed range.

A cross-axis single enveloping gear system includes a worm and a single enveloping gear that are operably engaged and configured to rotate about perpendicular axes. The cross-axis single enveloping gear system may be robust and cost effective. A cross-axis helical gear system includes a worm and a helical gear that are operably engaged and configured to rotate about perpendicular axes. A cross-axis helical gear system may be configured for quieter operation than a cross-axis single enveloping gear system.

A normal-strength power length adjuster system includes a leadscrew capable of withstanding an axial forces of at least 19 kN. The leadscrew for the normal-strength power length adjuster system may have trapezoidal threads designated by Tr 8×3 (P1.5) (8 mm nominal diameter, 3 mm lead, and 1.5 mm pitch). An enhanced-strength power length adjuster system includes a lead screw capable of withstanding axial forces of at least 25 kN. The leadscrew for the enhanced-strength power length adjuster system may have trapezoidal threads defined by Tr 9×3 (P1.5) (9 mm nominal diameter, 3 mm lead, and 1.5 mm pitch).

Speed classifications may be achieved by a combination of gear ratio and motor parameters (e.g., speed). In various implementations, a gearbox according to the principles of the present disclosure may accommodate gear systems having linear adjustment speeds ranging from 17 mm/s to 85 mm/s. In one implementation, a comfort speed system may be configured to have an average linear adjusting speed ranging from 17 to 22 mm/s. The comfort speed system may have a maximum electrical motor rotational speed of about 3,900 rpm. The comfort speed system may have a gear ratio of at least 6.5:1. In another implementation, a high speed system may be configured to have an average linear adjustment speed ranging from 50 mm/s to 55 mm/s. The high speed system may have a maximum electrical motor rotational speed of about 4,900 rpm. The high speed system may have a gear ratio of at least 3.333:1. In yet another implementation, a ultra-high speed system may be configured to have an average linear adjustment speed ranging from 80 mm/s to 85 mm/s, for example. The ultra-high speed system may have a maximum electrical motor rotational speed of about 6,900 rpm. The ultra-high speed system may have a gear ratio of at least 2.6:1.

A universal gearbox according to the principles of the present disclosure may accommodate any combination of the above gear types, strengths, and speeds. That is, a single gearbox design may be provided in an assembly setting for subsequently accommodating any combination of the above options. Example implementations are described below.

Referring to FIGS. 15A-15D, an adjustment assembly 24 h according to the principles of the present disclosure is provided. The structure and function of the adjustment assembly 24 h may be substantially similar to that of the adjustment assembly 24 (FIGS. 1-3), apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “h”) are used to identify those features that have been modified.

The adjustment assembly 24 h includes a spindle screw or lead screw 56 h having outer threads 66 h and an adjustment subassembly 58 h. The adjustment subassembly 58 h includes a first gear or cylindrical worm 80 h having helical outer threads 82 h, a second gear or enveloping worm 86 h having external teeth 84 h and internal thread 90 h, a pair of bearing bushings 78, and a gearbox assembly 1200. The gearbox assembly 1200 includes a gearbox 400 a and a plurality of fasteners 1202. The gearbox 400 a includes first and second portions 402 a, 404 a. While not shown, the adjustment subassembly 58 h may further include a support frame (e.g., support frame 74 of FIGS. 1-3) and a pair of cover shells (e.g., first and second cover shells 116, 118 of FIGS. 1-3). The adjustment assembly 24 h may alternatively include any of the other gearbox assemblies described herein.

The threads 66 h of the spindle screw 56 h may be trapezoidal and defined by Tr 9×3 (P1.5) (9 mm nominal diameter, 3 mm lead, and 1.5 mm pitch). The adjustment assembly 24 h may have a minimum axial strength of 25 kN and be considered an enhanced-strength adjustment assembly. The second gear 86 h may be a single enveloping worm gear. Therefore, the adjustment assembly 24 h may be considered to have a cross-axis single enveloping gear system. The adjustment assembly 24 h may be configured to be a comfort speed system via gear ratio and motor parameters.

With reference to FIGS. 16A-16E, an adjustment assembly 24 i according to the principles of the present disclosure is provided. The structure and function of the adjustment assembly 24 i may be substantially similar to that of the adjustment assembly 24 (FIGS. 1-3), apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “i”) are used to identify those features that have been modified.

The adjustment assembly 24 i includes a spindle screw or lead screw 56 h having outer threads 66 h and an adjustment subassembly 58 i. The adjustment subassembly 58 i includes a first gear or cylindrical worm 80 i having helical outer threads 8 i 2, a second or helical gear 86 i having external teeth 84 i and internal thread 90 i, a pair of bearing bushings 78, a pair of washers 1600, a gearbox assembly 1200, a pair of cover shells 116, 118, and a support frame 74. The gearbox assembly 1200 includes a gearbox 400 a and a plurality of fasteners 1202. The gearbox 400 a includes first and second portions 402 a, 404 a. The adjustment assembly 24 i may alternatively include any of the other gearbox assemblies described herein.

The helical gear 86 i includes two cylindrical bearing surfaces 162 i. The external teeth 84 i extend in a space between the bearing surfaces 162 i. Each washer 1600 is disposed on a respective one of the bearing surfaces 1602 between the external teeth 84 i and a respective one of the bearing bushings 78. Each washer 1600 includes a retention feature, such as a tab 1604, that engages the helical gear 86. The tab 1604 may reduce or prevent rotation of the washer 1600 with respect to the helical gear 86 i.

The adjustment assembly 24 i includes the spindle screw 56 h having the threads 66 h defined by Tr 9×3 (P1.5) (9 mm nominal diameter, 3 mm lead, and 1.5 mm pitch). The adjustment assembly 24 i may have a minimum axial strength of 25 kN and be considered an enhanced-strength adjustment assembly. The second gear 86 i may be a helical gear. Therefore, the adjustment assembly 24 i may be considered to have a cross-axis helical gear system. The adjustment assembly 24 i may be configured to be a comfort speed system via gear ratios and motor parameters.

Referring to FIGS. 17A-17D, an adjustment assembly 24 j according to the principles of the present disclosure is provided. The structure and function of the adjustment assembly 24 j may be substantially similar to that of the adjustment assembly 24 (FIGS. 1-3), apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “j”) are used to identify those features that have been modified.

The adjustment assembly 24 j includes a spindle screw or lead screw 56 j having outer threads 66 j and an adjustment subassembly 58 j. The adjustment subassembly 58 j includes a first gear or cylindrical worm 80 j having helical outer threads 82 j, a second gear or enveloping worm 86 j having external teeth 84 j and internal thread 90 j, a pair of bearing bushings 78, and a gearbox assembly 1200. The gearbox assembly 1200 includes a gearbox 400 a and a plurality of fasteners 1202. The gearbox 400 a includes first and second portions 402 a, 404 a. The adjustment assembly 24 j may alternatively include any of the other gearbox assemblies described herein. While not shown, the adjustment subassembly 58 j may further include a support frame (e.g., support frame 74 of FIGS. 1-3) and a pair of cover shells (e.g., first and second cover shells 116, 118 of FIGS. 1-3).

The threads 66 j of the spindle screw 56 j may be trapezoidal and defined by Tr 8×3 (P1.5) (8 mm nominal diameter, 3 mm lead, and 1.5 mm pitch). The adjustment assembly 24 j may have a minimum axial strength of 19 kN and be considered a normal-strength adjustment assembly. The second gear 86 j may be a single enveloping worm gear. Therefore, the adjustment assembly 24 j may be considered to have cross-axis single enveloping orthogonal gear system. The adjustment assembly 24 j may be configured to be a high speed system via gear ratios and motor speed.

Referring to FIGS. 18A-18D, an adjustment assembly 24 k according to the principles of the present disclosure is provided. The structure and function of the adjustment assembly 24 k may be substantially similar to that of the adjustment assembly 24 (FIGS. 1-3), apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “k”) are used to identify those features that have been modified.

The adjustment assembly 24 k includes a spindle screw or lead screw 56 j having outer threads 66 j and an adjustment subassembly 58 k. The adjustment subassembly 58 k includes a first gear or cylindrical worm 80 k having helical outer threads 82 k, a second gear or enveloping worm 86 k having external teeth 84 j and internal thread 90 k, a pair of bearing bushings 78, a pair of washers 1600, and a gearbox assembly 1200. The gearbox assembly 1200 includes a gearbox 400 a and a plurality of fasteners 1202. The gearbox 400 a includes first and second portions 402 a, 404 a. The adjustment assembly 24 k may alternatively include any of the other gearbox assemblies described here. While not shown, the adjustment subassembly 58 k may further include a support frame (e.g., support frame 74 of FIGS. 1-3) a pair of cover shells (e.g., first and second cover shells 116, 118 of FIGS. 1-3).

The threads 66 j of the spindle screw 56 j may be trapezoidal and defined by Tr 8×3 (P1.5) (8 mm nominal diameter, 3 mm lead, and 1.5 mm pitch). The adjustment assembly 24 j may have a minimum axial strength of 19 kN and be considered a normal-strength adjustment assembly. The second gear 86 k may be a single enveloping worm gear. Therefore, the adjustment assembly 24 k may be considered to have a cross-axis single enveloping gear system. The adjustment assembly 24 k may be configured to be a high speed system.

With reference to FIGS. 19A-19D, an adjustment assembly 24 m according to the principles of the present disclosure is provided. The structure and function of the adjustment assembly 24 m may be substantially similar to that of the adjustment assembly 24 (FIGS. 1-3), apart from any exceptions described below and/or otherwise shown in the figures. Accordingly, the structure and/or function of similar features will not be described again in detail. In addition, like reference numerals are used hereinafter and in the drawings to identify like features, while like reference numerals containing letter extensions (i.e., “m”) are used to identify those features that have been modified.

The adjustment assembly 24 m includes a spindle screw or lead screw 56 j having outer threads 66 j and an adjustment subassembly 58 m. The adjustment subassembly 58 m includes a first gear or cylindrical worm 80 j having helical outer threads 82 j, a second gear or enveloping worm 86 m having external teeth 84 m and internal thread 90 m, a pair of bearing bushings 78, a pair of washers 1600, and a gearbox assembly 1200. The gearbox assembly 1200 includes a gearbox 400 a and a plurality of fasteners 1202. The gearbox 400 a includes first and second portions 402 a, 404 a. The adjustment assembly 24 m may alternatively include any of the other gearbox assemblies described here. While not shown, the adjustment subassembly 58 m may further include a support frame (e.g., support frame 74 of FIGS. 1-3) a pair of cover shells (e.g., first and second cover shells 116, 118 of FIGS. 1-3).

The threads 66 j of the spindle screw 56 j may be trapezoidal and defined by Tr 8×3 (P1.5) (8 mm nominal diameter, 3 mm lead, and 1.5 mm pitch). The adjustment assembly 24 j may have a minimum axial strength of 19 kN and be considered a normal-strength adjustment assembly. The second gear 86 m may be an enveloping worm gear. Therefore, the adjustment assembly 24 k may be considered to have an enveloping orthogonal gear system. The adjustment assembly 24 m may be configured to be a ultra-high speed system.

In accordance with the principles of the present disclosure, a power length adjustment assembly may include a gearbox assembly, a gear system, and a spindle screw. The gearbox assembly may include a gearbox and a plurality of fasteners. The gearbox may be an open-type gearbox or a close-type gearbox. The gearbox may include two parts or portions having mating surfaces with three-dimensional curvature, such as ellipsoidal, conical, or spherical. The fasteners may include screws (e.g., self-tapping screws), rivets (e.g., discrete rivets, integral rivets), bolts, or any combination thereof. The gear system may be an enveloping orthogonal gear system or a helical orthogonal gear system. The gear system may be configured to be a comfort speed system, a high speed system, or a ultra-high speed system. The spindle screw may be a normal-strength lead screw or an enhanced-strength lead screw.

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A gearbox for a vehicle seat adjustment mechanism comprising: a first portion including a first body, the first body defining a first longitudinal recess and a first peripheral recess in fluid communication with the first longitudinal recess, and including a first curved surface, the first curved surface being concave; and a second portion including a second body, the second body define a second longitudinal recess and a second peripheral recess in fluid communication with the second longitudinal recess, and including a second curved surface, the second curved surface being convex and having an equal and opposite curvature compared to the first curved surface, wherein in an assembled configuration: the first curved surface is in contact with the second curved surface, the first longitudinal recess communicates with the second longitudinal recess to define a longitudinal passage, and the first peripheral recess communicates with the second peripheral recess to define a peripheral receptacle.
 2. The gearbox of claim 1, wherein the first curved surface and the second curved surface both define (i) a portion of an ellipsoidal surface, (ii) a portion of a conical surface, or (iii) a portion of a spherical surface.
 3. The gearbox of claim 1, wherein the first curved surface and the second curved surface both define a portion of an ellipsoidal surface, the ellipsoidal surface having a first radius in a range of 190 mm to 200 mm and a second radius in a range of 240 to 250 mm.
 4. The gearbox of claim 1, wherein the first curved surface and the second curved surface both define a portion of a conical surface, the conical surface defining an average opening angle in a range of 165° to 172°.
 5. The gearbox of claim 1, wherein the first curved surface and the second curved surface both define a portion of a spherical surface, the spherical surface having a radius in a range of 190 mm to 200 mm.
 6. The gearbox of claim 1, wherein: one of the first portion and the second portion includes a frusto-conical projection extending from a respective one of the first curved surface and the second curved surface, the other of the first portion and the second portion includes a frusto-conical receptacle defined by a respective one of the first curved surface and the second curved surface, and in the assembled configuration, the frusto-conical receptacle receives the frusto-conical projection.
 7. The gearbox of claim 6, wherein: the one of the first portion and the second portion further includes an annular projection extending from the respective one of the first curved surface and the second curved surface, the annular projection being disposed around a base of the frusto-conical projection and coaxial with the frusto-conical projection, the other of the first portion and the second portion further includes an annular depression defined by a respective one of the first curved surface and the second curved surface, the annular depression coaxial with the frusto-conical receptacle, and in the assembled configuration, the annular depression receives the annular projection.
 8. The gearbox of claim 7, wherein the frusto-conical projection includes a first frusto-conical projection and a second frusto-conical projection, the frusto-conical receptacle includes a first frusto-conical receptacle and a second frusto-conical receptacle, the annular projection includes a first annular projection and a second annular projection, and the annular depression includes a first annular depression and a second annular depression.
 9. The gearbox of claim 1, further comprising: an elastic layer disposed on at least one of the first curved surface or the second curved surface.
 10. The gearbox of claim 1, wherein: one of the first portion and the second portion includes an integral rivet extending from a respective one of the first curved surface and the second curved surface, and the other one of the first portion and the second portion includes an aperture defined in a respective one of the first curved surface and the second curved surface, the aperture being configured to receive a portion of the integral rivet.
 11. The gearbox of claim 1, further comprising: a plurality of fasteners configured to couple the first portion and the second portion to each other.
 12. The gearbox of claim 1, wherein: the gearbox is configured to house at least a portion of a cross-axis gear system and a spindle screw, and the cross-axis gear system includes a first gear in operative communication with a second gear, the second gear being in operative communication with the spindle screw.
 13. The gearbox of claim 12, wherein the gear system is configured to operate at one of: (i) a comfort speed having a linear adjusting speed ranging from 17 mm/s to 22 mm/s, (ii) a high speed having a linear adjusting speed ranging from 50 mm/s to 55 mm/s, or (iii) a ultra-high speed having a linear adjusting speed ranging from 80 mm/s to 85 mm/s.
 14. The gearbox of claim 12, wherein the first gear is a cylindrical worm gear and the second gear is one of a helical gear or a single enveloping worm gear.
 15. A vehicle seat adjustment assembly comprising: a gearbox assembly including, a first portion including a first body, the first body defining a first longitudinal recess and a first peripheral recess in fluid communication with the first longitudinal recess, and including a first curved surface, the first curved surface being concave, and a second portion including a second body, the second body defining a second longitudinal recess and a second peripheral recess, and including a second curved surface, the second longitudinal recess cooperating with the first longitudinal recess to define a longitudinal passage, the second peripheral recess cooperating with the first peripheral recess to define a peripheral receptacle, the second curved surface being convex, having an equal and opposite curvature compared to the first curved surface, and being in contact with the first curved surface; a gear system including, a first gear disposed at least partially within the peripheral receptacle, the first gear including a first external thread, the first gear configured to rotate about a first axis, and a second gear disposed at least partially within the longitudinal passage, the second gear including external teeth and an internal thread and defining a gear passage, the external teeth in operative communication with the first external thread, the second gear configured to rotate about a second axis perpendicular to the first axis; and a spindle screw extending through the gear passage and including a second external thread, the second external thread in operative communication with the internal thread.
 16. The vehicle seat adjuster assembly of claim 15, wherein the first curved surface and the second curved surface both define (i) a portion of an ellipsoidal surface, (ii) a portion of a conical surface, or (iii) a portion of a spherical surface.
 17. The vehicle seat adjustment assembly of claim 15, wherein the second gear is one of (i) a helical gear or (ii) a single enveloping worm gear.
 18. The vehicle seat adjustment assembly of claim 15, wherein: the second external thread is a trapezoidal thread, and the spindle screw has a 3 mm lead, a 1.5 mm pitch, and one of a (i) 8 mm nominal diameter and (ii) a 9 mm nominal diameter.
 19. The vehicle seat adjustment assembly of claim 15, wherein the gear system is configured to operate at one of: (i) a comfort speed having a linear adjusting speed ranging from 17 mm/s to 22 mm/s, (ii) a high speed having a linear adjusting speed ranging from 50 mm/s to 55 mm/s, or (iii) a ultra-high speed having a linear adjusting speed ranging from 80 mm/s to 85 mm/s.
 20. The gearbox assembly of claim 15, wherein: one of the first portion and the second portion includes a frusto-conical projection and an annular projection extending from a respective one of the first curved surface and the second curved surface, the annular projection being disposed around a base of the frusto-conical projection and coaxial with the frusto-conical projection, other of the first portion and the second portion includes a frusto-conical receptacle and an annular depression defined by a respective one of the first curved surface and the second curved surface, the annular depression coaxial with the frusto-conical receptacle, and the frusto-conical receptacle is configured to receive the frusto-conical projection and the annular depression is configured to receive the annular projection. 